34 research outputs found
Refinements of Miller's Algorithm over Weierstrass Curves Revisited
In 1986 Victor Miller described an algorithm for computing the Weil pairing
in his unpublished manuscript. This algorithm has then become the core of all
pairing-based cryptosystems. Many improvements of the algorithm have been
presented. Most of them involve a choice of elliptic curves of a \emph{special}
forms to exploit a possible twist during Tate pairing computation. Other
improvements involve a reduction of the number of iterations in the Miller's
algorithm. For the generic case, Blake, Murty and Xu proposed three refinements
to Miller's algorithm over Weierstrass curves. Though their refinements which
only reduce the total number of vertical lines in Miller's algorithm, did not
give an efficient computation as other optimizations, but they can be applied
for computing \emph{both} of Weil and Tate pairings on \emph{all}
pairing-friendly elliptic curves. In this paper we extend the Blake-Murty-Xu's
method and show how to perform an elimination of all vertical lines in Miller's
algorithm during Weil/Tate pairings computation on \emph{general} elliptic
curves. Experimental results show that our algorithm is faster about 25% in
comparison with the original Miller's algorithm.Comment: 17 page
Post-quantum cryptography
Cryptography is essential for the security of online communication, cars and implanted medical devices. However, many commonly used cryptosystems will be completely broken once large quantum computers exist. Post-quantum cryptography is cryptography under the assumption that the attacker has a large quantum computer; post-quantum cryptosystems strive to remain secure even in this scenario. This relatively young research area has seen some successes in identifying mathematical operations for which quantum algorithms offer little advantage in speed, and then building cryptographic systems around those. The central challenge in post-quantum cryptography is to meet demands for cryptographic usability and flexibility without sacrificing confidence.</p
Steganography: a class of secure and robust algorithms
This research work presents a new class of non-blind information hiding
algorithms that are stego-secure and robust. They are based on some finite
domains iterations having the Devaney's topological chaos property. Thanks to a
complete formalization of the approach we prove security against watermark-only
attacks of a large class of steganographic algorithms. Finally a complete study
of robustness is given in frequency DWT and DCT domains.Comment: Published in The Computer Journal special issue about steganograph
Computing Optimal Ate Pairings on Elliptic Curves with Embedding Degree and
Much attention has been given to efficient computation of pairings on elliptic curves with even embedding degree since the advent of pairing-based cryptography. The existing few works in the case of odd embedding degrees require some improvements.
This paper considers the computation of optimal ate pairings on elliptic curves of embedding degrees k=9, 15 \mbox{ and } 27 which have twists of order three. Mainly, we provide a detailed arithmetic and cost estimation of operations in the tower extensions field of the corresponding extension fields. A good selection of parameters
enables us to improve the theoretical cost for the Miller step and the final exponentiation using the lattice-based method comparatively to the previous few works that exist in these cases. In particular for and we obtained an improvement, in terms of operations in the base field, of up to and respectively in the computation of the final exponentiation.
Also, we obtained that elliptic curves with embedding degree present faster results than BN curves at the -bit security levels.
We provided a MAGMA implementation in each case to ensure the correctness of the formulas used in this work
Optimal Ate Pairing on Elliptic Curves with Embedding Degree and
Much attention has been given to the efficient computation of pairings on
elliptic curves with even embedding degree since the advent of pairing-based
cryptography. The few existing works in the case of odd embedding degrees
require some improvements. This paper considers the computation of optimal ate
pairings on elliptic curves of embedding degrees , , which have
twists of order three. Our main goal is to provide a detailed arithmetic and
cost estimation of operations in the tower extensions field of the
corresponding extension fields. A good selection of parameters enables us to
improve the theoretical cost for the Miller step and the final exponentiation
using the lattice-based method as compared to the previous few works that exist
in these cases. In particular, for , , we obtain an improvement, in
terms of operations in the base field, of up to 25% and 29% respectively in the
computation of the final exponentiation. We also find that elliptic curves with
embedding degree present faster results than BN12 curves at the 128-bit
security level. We provide a MAGMA implementation in each case to ensure the
correctness of the formulas used in this work.Comment: 25 page
Attribute-based encryption with granular revocation
National Research Foundation (NRF) Singapor
Adequate Elliptic Curve for Computing the Product of n Pairings
Many pairing-based protocols require the computation of the product
and/or of a quotient of n pairings where n > 1 is a natural integer.
Zhang et al.[1] recently showed that the Kachisa-Schafer and Scott family
of elliptic curves with embedding degree 16 denoted KSS16 at the 192-bit
security level is suitable for such protocols comparatively to the Baretto-
Lynn and Scott family of elliptic curves of embedding degree 12 (BLS12).
In this work, we provide important corrections and improvements to their
work based on the computation of the optimal Ate pairing. We focus on
the computation of the nal exponentiation which represent an important
part of the overall computation of this pairing. Our results improve by
864 multiplications in Fp the computations of Zhang et al.[1]. We prove
that for computing the product or the quotient of 2 pairings, BLS12 curves
are the best solution. In other cases, specially when n > 2 as mentioned in
[1], KSS16 curves are recommended for computing product of n pairings.
Furthermore, we prove that the curve presented by Zhang et al.[1] is not
resistant against small subgroup attacks. We provide an example of KSS16
curve protected against such attacks
Lossy Cryptography from Code-Based Assumptions
Over the past few decades, we have seen a proliferation of advanced cryptographic primitives with lossy or homomorphic properties built from various assumptions such as Quadratic Residuosity, Decisional Diffie-Hellman, and Learning with Errors. These primitives imply hard problems in the complexity class (statistical zero-knowledge); as a consequence, they can only be based on assumptions that are broken in . This poses a barrier for building advanced primitives from code-based assumptions, as the only known such assumption is Learning Parity with Noise (LPN) with an extremely low noise rate , which is broken in quasi-polynomial time.
In this work, we propose a new code-based assumption: Dense-Sparse LPN, that falls in the complexity class and is conjectured to be secure against subexponential time adversaries. Our assumption is a variant of LPN that is inspired by McEliece\u27s cryptosystem and random k\mbox{-}XOR in average-case complexity. Roughly, the assumption states that
for a random (dense) matrix , random sparse matrix , and sparse noise vector drawn from the Bernoulli distribution with inverse polynomial noise probability.
We leverage our assumption to build lossy trapdoor functions (Peikert-Waters STOC 08). This gives the first post-quantum alternative to the lattice-based construction in the original paper. Lossy trapdoor functions, being a fundamental cryptographic tool, are known to enable a broad spectrum of both lossy and non-lossy cryptographic primitives; our construction thus implies these primitives in a generic manner. In particular, we achieve collision-resistant hash functions with plausible subexponential security, improving over a prior construction from LPN with noise rate that is only quasi-polynomially secure